[PaulKeeble]

And if its sold 5 times in the year its 5x the GDP. Of course the value of the painting hasn't changed and their remains only 1.

[sokoloff]

Resales of previously sold (used) goods are not included in GDP.

Services to facilitate selling [auction fees, commissions, shipping, etc.] are new services and so get counted, but the underlying asset's resale is not.